If you read Shally's blog Randy Bailey is a LinkedIn Group Maniac then you're already aware that LinkedIn groups are a great way to expand your LinkedIn network with people who have an interest in areas that interest you. Hat tip to Stacy Zapar who pointed me to Jason Bailes' very cool LinkedIn Groups Search. Here's what Jason has to say about his creation:

Search by keywords for groups to join on LinkedIn.com.

There are thousands of groups to join on LinkedIn. However, LinkedIn does not yet have a "group search" feature. I have noticed many of us LinkedIn members asking how to find and join groups. My goal was to provide us with a simple solution.

New groups may take longer to display in the search results pages. Therefore, it is advised to search often for the types of groups that interest you the most.

Supports Google's Advanced Search features.

Examples:

"alumni", "marketing -web", "certified OR certification".

searches 3 sites, including: www.linkedin.com/groupInvitation*, www.linkedin.com/e/gis/*, www.linkedin.com/static?key=groups*